Add dialer simulation functionality into simulator.

When users press "enable simulator mode" button, one PhoneAccount associated with SimulatorConnectionService will be registered into platform so users can make fake call through dialer. To end this, simply press "disable simulator mode" button.

Bug: 71898328
Test: On a local device.
PiperOrigin-RevId: 186707002
Change-Id: Ic584bcd88bb52ac0b96c4cb214ad8edc70cf24d4